Variable ratio steering assembly



Oct 12, 1948. I j BOOTH 2,451,061

VARIABLE RATIO STEERING ASSEMBLY Filed Oct. 27, 1945 2 Sheets-Sheet l t A fl E f v 1; W

J. H. BOOTH VARIABLE RATIO STEERING ASSEMBLY 2 Shets-Sheet 2 Filed Oct. 2'7, 1945 1522.222 02' #7917785 H Boo/7% m m. NH

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Patented Get. 12, 1948 VARIABLE RATIO STEERING ASSEMBLY James H. Booth, Detroit, Mich., assignor to Thompson Products, Inc., Cleveland, Ohio, a-

corporation of Ohio Application October 27, 1945, Serial-No. 625,092-

Claims. 1

This invention relates to steering mechanisms and the like wherein rotation of a'steering wheel reciprocates a slidable part, and wherein reciprocal motion of the sli'dable part is selectively resolved into rotating motion for steering dirigible wheels or the like.

Specifically, the invention deals with a mechanical movement especially suited for automotive steering assemblies, wherein a rotating part reciprocates a driven part and wherein reciprocal. movement of the driven part is resolved into desired rotating movement in amountsv determined by the selected position of a control member.

In my copending application, Serial No. 589,039, filed April 18, 1945, now Patent No. 2,417,073, issued March 11, 1947, entitled: Variable gear ratio steering assembly, of which thepresent application is a continuation in part, there are described and claimed steering mechanisms where in a steering shaft reciprocates a pitman arm shaft through a worm and gear arrangement, and wherein the pitman arm shaft controls the swinging movement of a pitman arm to steer dirigible Wheels.

The present invention is concerned with improvements for such assemblies. that bring. about. easier operation and better balanced transfer of operating stresses.

In accordance with the present invention a. compact variable ratio steering assembly is provided wherein relatively movable parts are carried on self-aligning bearings that will not transmit bending or twisting loads and at the same time will accommodate misalignment of parts.

Thus, in accordance with the presentinven-tion, a casing is provided with opposed open. ends and an operating chamber between these. open ends. One open end of the casing supports a. self-aligning bearing. The other open end of the casing fixedly supports a sleeve which projects into theoperating chamber. The inner end of this sleeve carries a self-aligning bearing therearound. A tube is slidably mounted in the self-aligning hearing carried by the firstmentioned open end of the casing and on the self-aligning bearing carried around the sleeve. The tubeis free to reciprocate on the self-aligning bearings.

Another self-aligning bearing is secured in the sleeve and held therein against axial movement. Still another self-aligning bearing. is slidably mounted in the tube. A worm is rotatably sup.- ported in the two last-mentioned bearings, The tube rotatably supports diametrically opposed worm followers or gears. These. gears are in- 2 so that they will always be in full meshed engagement with the worm. A steering shaft projects through the sleeve to rotate the worm and thereby move the worm follower gears and tube. along reciprocal paths relative. to the casing.

The tube projects from the casing and has a pitman arm fixedly depending from its projected end. A link is connected to the tube through a ball and socket or' other universal joint. This. link has a pivot anchor which can be shifted. ,As the tube is reciprocated, the link will resolve this. reciprocal movement into rotating movement... thereby swinging the pitman arm. The. degree of resolution of such movement is varied at will by shifting the pivot anchor for the link.

It is, then, an object of the present invention. to provide an improved variable ratio steering assembly of the type disclosed and claimed in my copending application Serial 589,039. filed April 18, 1945.

A still further object of the invention is. to. provide a compact variable ratio steering unitwhich. is easy to operate and which has self-aligning, bearings accommodating misalignment of parts.

A further object of the invention is. to. provide. a very small, efliciently operating.v mechanical movement unit wherein rotation of a driving part reciprocates a driven part, and wherein reciprocal movement of the driven part is resolved into a controlled degree of rotating movement.

Other and further objects of the invention will be apparent to those. skilled in the art fromthe following detailed description: of the annexed sheets of drawings which, by way of preferred example only, illustrate one embodiment ofthe invention.

On the. drawings:

Figure 1 is a fragmentary top plan view, with parts broken away and shown inhorizontal cross section, of anautomotive vehicle chassis equipped with independently suspended dirigi-ble wheels;

and a variable ratio steering unit according. to this invention.

Figure 2 is a vertical cross-sectional; view, with parts in elevation, taken. substantially along the line ]III of Figure 1.

Figure 3 is anaxial cross-sectional View, with parts in top plan, of thevariable ratio steering unit of this invention;

Figure 4 is a fragmentary top plan View of the unit of this invention illustrating somewhat? diagrammatically the manner in wl'richthedegree' of resolution of reciprocal movement into rotating clined. at the same angle as the pitch of the worm movement is controlled:

As shown on the drawings:

In Figures 1 and 2, the reference numeral I designates generally the chassis of an automotive vehicle. The chassis Ill has side frame beams I I, I I and a cross beam I2. Independent wheel links or. sub-axles, I3, I3 are pivotally supported on the cross beam I2 and dirigible wheels I4, I4 are rotatably mounted on spindles I5, I5 pivotally carried by the sub-axles I3, I3. Each spindle I5 has a steering arm I5a projecting therefrom and these arms I5a are connected through tie rods I6, IS with a center steering arm I! that is pivoted to the cross beam I2 by means of a pivot pin I8.

A drag link I9 is also connected to the center steering arm [1. The tie rods I6 are connected to the steering arms I'5a through tie rod joints such as ball joints. In addition, the tie rods I6 and drag link I9 have ball and socket joint connections with the center steering arm so that the Wheels I4 can rise and fall independently of each other andrelative to the cross beam I2.

. The drag link I9 is connected through a ball and socket joint to the lower end of a pitman arm 20. This pitman arm has an eye end or hub 20a fixedly securedvto the pitman arm shaft 2| of the Variable ratio steering unit 22 of this invention. 7

As best shown in Figure 3, the unit 22 includes a casing 23 defining an operating chamber 24.

This casing 23 is adapted to be fixedly mounted on a side frame beam I I of the automotive chassis l8 shown in Figures 1 and 2. The casing has open endswith a collar 25 projecting from one open end thereof and with a flange 26 on the other open end thereof. The openings in the ends of the casing are aligned.

A first bearin 21 is mounted in the collar 25 on concave supporting rings 28 which permit the bearing 21 to tilt. A self-aligning bearingis thus provided. The rings 28 are clamped between a shoulder-25a at the inner end of the collar 25 and a clamping nut 29 threaded into the outer end of the collar.

'A flanged sleeve 30 projects into the other open end of the casing 23 and has its flanged end 30a thereof affixed to the flange 25 by means of bolts 26a. The inner end of the sleeve 30 extends into the operating chamber 24 and has a rounded convex peripheral portion 30b tiltably receiving a second bearing 3I. r p

The pitman' arm shaft, 2I is in the form of a hollow'tube and is slidably mounted in the hearing 21 and on the bearing 3I'. Thus the bearing 27 surrounds the outside of the tube while the bearin 3I' is'in'side of the tube.

A third bearing 32, preferably in the form of a self-aligning anti-friction roller bearing, is mounted in the sleeve 30 at the inner end thereof. The bearing 32 includes inner race rings 32a surrounded by roller bearings 32b in outer race rings 320 having a spherically convex outer peripheral portion seated in concave rings 33. These concave rings 33 are bottomed on an inturned flange 300 at the inherend of the sleeve 30 and are se cured against axial movement in the sleeve by a tube 34 which is threaded into the outer end of the sleeve 30 and held in fixed relation therewith by means of a locking nut 34a. The bearing 32 is thus held against axial movement relative to the tube 30 but can tilt relative to the tube.

A fourth bearin 35 is slidably mounted in the tube 2] in spaced opposed relation from the bearing 32, and includes a ring 35a havinga cylindrical outer periphery slidably engaging the inner worm 3'1, the worm followers will be caused to cylindrical surface'of the tube 2| together with a ball member 35b rockably seated on the concave inner surface of the ring 3501., The bearing 35 is therefore self-aligning. Passages such as 36 are provided through the ring 35a to equalize the pressure on opposite sides of the ring as the tube 2I is reciprocated.

A worm 3'! is carried in the bearings 32 and 35 and is held against axialmoyement relative to the bearings by means of nuts 38 engaging the bearing part 3% together with nuts 39 engaging the bearing 32a. Shoulders 31a. and 31b on the ends of the worm are bottomed on the bearing parts 35b and 32a respectively so that the bearings are clamped against axial movement relative to the worm. Since the bearing 32 is also clamped against axial movement relative to the sleeve 30, the worm is restrained against axial movements and can only rotate in the casing 23.

A steering shaft 40 extends from the worm 31 through the sleeve 30 and tube 34and is integral with the wormor directly coupled therewith;

The pitman arm shaft or' tube 2| has apertures 2la on diametrically opposed sides thereof;

. in the operating chamber 24. Lugs or-ears 4!: are;

Welded or otherwise fixedly secured to the tube 2I alongside of the apertures 2Ia.- {These lugs 4| carry pins or axles 42 having eccentric end portions 42a seated in bearing-engagement in apertures in the lugs. Rotationof-the pins will therefore shift them towardand "awayfrom the 7 tube 2I. The pins are fixedly lockedin adjusted non-rotatable relation relativeto the lugs 4l by' means of keys 43 which fit into groovesprovided in oneoi the lugs of each pair and also fit into key slots in the end of each -pin. Anut 44. on each pin holds the key 43 in theselected groove and slot. The arrangement is such that the nut can be loosened, the key removed,-the .pinroa. tated to eccentrically shift itseaxi's to the desired position, the key reinserted in aligned grooves and slots of the ear and pin respectively 'and the nut.

tightened to hold the pin iniits set po'sition fo'r freely around the race rings-45 ."onthe ball bear ings 46.

The lugs 4I carry the pins .42 ininclinedrela-Q. tion to the tube 2I' so that-the. .followersiI-lwilh be pitched to the same inclination asthe'teeth of the worm 31, The followers .4Lproiect through the apertures Zia and have teiethrtherearound meshing with the worm 31 as shown. ,JIhle in: clined cam followers will havehtheir peripheral teeth engaging the worm teeth at the pitch angle of the worm. In the event of wear betweenthe engaging teeth, the pins 42 can be rotated and their eccentric ends 42a will shift 'the pins, to move the followers 41 towardthe. worm thereby taking up. wearj between the parts and preventing looseness. t g V g V,

When the shaft 40 is rotatedv to rctate the move along the length of the worm to reciprocate w the tube 2|. Rotation oftheshaft AOQ'therefore;

effects reciprocation of the pitman armishaftpr.

tube 2I', and this reciprocatio is not interfered. with by the steeringlinkag'e'eventhoughthe pit man arm '20 moves with the shaftortube' 2I since 1' the drag link I9.has ball iointsa'tl he ends thereof. andcanreadly swing to accommodate the recip -Q ine ements; s 1

The swinging of the drag link -|9 brought about by reciprocation of the pitman arm tube or shaft 2| and the pitman arm 20 is in a fore and aft direction relative to the chassis l and will have no steering effect on the wheels M. The tube 2|, as explained above, slides in the bearing 2'| and on the bearing 3! At the same time, the tube 2| slides over the bearing 35 since this bearing is fixed against axial movement.

The top of the pitman arm hub 20a has a ball ended stud 38 mounted thereon -as indicated in dotted lines in Figures 3 and 4 and as shown in solid lines in Figure 2. A rigid link 49 has a ball socket end 4% receiving the ball end of the stud 8 in universal joint relation. This link 49 has a ball socket end on the other end thereof as best shown in Figure 4. A ball stud 50 mounted on an anchor plate 5| has the ball end thereof seated in this socket 492). The plate 5| has a fixed pivot 52 anchoring the plate to a side frame beam H of the chassis W as best shown in Figures 1 and 2. A control rod 53 is also pivoted to the plate 5| to swing the plate about its pivot 52. The control rod 53 extends to within convenient reach of the driver of the automobile and, if desired, can have an operating handle (not shown) on the dashboard of the vehicle, or adjacent the steering column (not shown).

ihe link 49 is, therefore, connected at its ends through universal joints with one end being secured to the hub 2G0 of the pitman arm 20 and with the other end being secured to a shiftable anchor plate 5|. The link can thus swing in all directions but, being rigid, it cannot elongate or contract.

As the pitman arm shaft or tube 2| is reciprocated to move the pitman arm hub 20a toward and away from the casing 23, the link 49 will resolve this reciprocal movement into rotating movement in an amount depending upon the setting of the plate 5|. Thus, as shown in Figure 4, when the plate Si is in the solid line position and the pitman arm hub 20a is reciprocated, the end of the link 49 aihxed to the hub 200, will move in the arcuate path A thereby swinging the pitman arm and shifting the drag link Hi to steer the wheels Hi. When the plate 5! is swung to the dotted line position, the path of movement of the link as will be along the arcuate path B and the pitman arm will wing to a greater extent.

The shifting pivot anchor for the link 49 thereby gives a selective control of the degree of resolution of reciprocal movement into rotating or active steering movement, and a variable ratio steering assembly is provided.

The opposed worm followers 41 and the tube 2| provide a balanced arrangement of gears to efficiently effect sliding of the pitman arm shaft or tube 2! upon rotation of the worm. The selfaligning bearings supporting the tube 2| will prevent binding and transfer of bending stresses. Likewise, the self -aligning bearings that rotatably support the worm will absorb binding movement that would otherwise interfere with free sliding of the tube 2|.

From the above descriptions it will be understood that the invention provides an improved compact, baianced, and easy acting variable ratio mechanical movement assembly of the type wherein rotating movement is efficiently transferred into sliding movement, and wherein this sliding movement is selectively resolved into rotating movement. Parts of the assembly are nested or telescoped in each other to reduce the overall size of the assembly.

. It wilt, of course, be understood that various details of Z'construction may be varied through a wide range without departing 'from the principles of-this invention and itiis, therefore, not the purpose to limit thepaten-t granted hereon otherwise than necessitated by the 'scopeof the appended claims.

LIclaim as my invention:

A steering assembly comprising a casing having open ends and defining an operating chamber therebetween, a first bearing tiltably mounted in one-open end of the casing, a sleeve projecting into the other open end of the casing and having a flanged end secured to the casing, a second bearing tiltably mounted on the sleeve in said operating chamber, a tube slid-ably mounted in the first bearing and on the second bearing and projecting out of the casing beyond the first bearing, a third bearing tiltably mounted in the sleeve, means in said sleeve holding the third bearing against axial movement, a fourth tiltable bearing slidable in the tube, a worm in said tube rot-atalbly carried in the third and fourth bearings, means holding the worm against axial movement relative to the third and fourth bearings, opposed worm gears rotatably mounted ,on the tube in said operating chamber of the casing and projecting through the tube into meshed engagement with the worm, means for rotating the worm to drive the gears for reciprocating the tube relative to the casing, a pitman arm depending from the tube outside of the casing, and a shiftable control link connected to said tube to selectively translate reciprocal movement of the tube and pitman arm into rotating movement for swinging the pitman arm.

2. In a selective mechanical movement assembly, a tube, a casing slidably supporting said tube, a worm rotatably mounted in said tube, a worm gear rotatably mounted on the tube in meshed engagement with said worm, means for rotating the worm to reciprocate the tube relative to the casing, a lever afiixed to the tube and depending therefrom, a link operatively connected to the tube for resolving sliding movement thereof into rotation to thereby swing the lever, and a shiftable pivot anchor for said link to selectively vary the degree of said resolving of movement.

3. A steering unit comprising a casing, a hollow pitman arm shaft slidably mounted in said casing, a worm fixedly mounted for rotation in said hollow shaft, a worm gear rotatably mounted on said hollow shaft in meshed engagement with said worm therein, means for rotating the worm to reciprocate the hollow shaft relative to the casing, a link member operatively connected to the hollow shaft, a pivot anchor for said link member, and means for shifting said pivot anchor, said link resolving reciprocal movement of the hollow shaft into rotative movement and said shiftable pivot anchor for the link determining the degree of said resolution of movement.

4. Aselective mechanical movement assembly comprising a slidably mounted tube, an arm mounted on said tube for comovement therewith, a rotatable driver in said tube, means connecting the driver with the tube to reciprocate the tube when the driver is rotated, a link conneced to said tube, and a shiftable anchor for said link, said link resolving reciprocal movement of the tube into rotative movement to swing the arm and the position of said shiftable anchor determining the degree of said resolution.

5. A compact steering unit comprising a casing,

a tube'insaid casingrand projecting therefrom, REFERENCES CITED self-aligning hearings in the casing slidably and rotatably mounting the tube in the casing, a

worm in the tube, self-aligning bearings in the file thls patent tube rotatably mounting the worm, means hold- 5 V ED STATES PATENTS ing the worm against axial movement, means Number Name e Date I drivingly connecting the worm and tube to re- 311,522 Andress b 2 13 1 ciprocate the tuloe when the worm is rotated, 1594767 Blas'chke 3' 192 means for resolving reciprocal movement of the L920 651 Mackenzie Aug 1 1933 tube into controlled amounts of rotative-move- 10 2,018,253 Best 19 5' ment. n

- 2,030,441 J S H- BOO I Ganz Feb 1111936 The following references are of record in the 

